The present invention relates to a passive device for indicating the incidence of electromagnetic radiation, as when a military vehicle is being sighted by an enemy laser-range finder.
In military engineering, enemy objects are measured with laser range finders in order to assure high accuracy of fire on the first firing. Such range finders operate in the near infrared (ruby laser at 694 nm, YAG laser at 1060 nm, or erbium laser at 1566 nm), or in the medium infrared (CO.sub.2 laser at 10.6 .mu.m).
The object of the present invention is to provide a passive means of warning to the driver of a military vehicle when his vehicle is being sighted by an enemy laser-range finder and, in this connection, to give him at least a general indication of the direction from which his vehicle is being sighted.
In U.S. Pat. No. 4,467,208, radiation detectors are disclosed as indicators of combustion or ignition processes and for the contact-less transfer of light signals between two relatively moving parts, the particular emphasis being on development of detector response to radiation in the ultraviolet region. These known detectors rely on a collector in the form of a light-guide fiber wound on a support, wherein the fiber has a core zone and an outer zone (cladding) of differing refractive index, and wherein the core material fluoresces when excited by ultraviolet radiation; the fluroescent light is conducted along the core to detector means at one or both ends of the core. These detectors are not suited to the above-stated object, but it is another object of the present invention to adapt and utilize some of the principles of said patent disclosure, in order to meet the directional and wavelength-response requirements for passive detection of a hostile laser sighting.